Torque wrench



May23,1939; A L DUNN 2,159,373

Tonarm WRENCH Filed April 10, 1937 3 Sheets-Sheet 3 INVENTOR. ALL ENDUN/V BY @W7 ATTORNEY.

Patented May 23, 1939 'roaQUE WRENCH Allen I. Dunn, Cedar Rapids, Iowa,assignor to.

Cedar Rapids Engineering' Company, Cedar Rapids, Iowa, a corporation ofIowa Application April 10, 1937, Serial No. 136,048

14 Claims.

This invention relates to wrenches, and more particularlyto a wrench forindicating the amount vof force or torque applied to the handle inrotating or attempting to rotate a nut or the like engaged by thewrench.`

It has been found, for instance, in the tightening of nuts on cylinderheads of internal combustion engines or in assembling precision devicessuch as air-craft engines and the like that it is ld very desirable totighten the nuts and bolts of such devices to certain known degrees.

Devices have been provided for this purpose in which hydraulic pistonshave been utilized for actuating oil pressure gauges to indicate the 3Utorque or force applied, but it has been found` that such devices havebeen expensive to constructand maintain, are diflicult to'seal, and arenot entirely accurate because of the friction of the parts and theinaccuracies of the production made gauges which it is necessary toemploy.

It is a general object of myinvention -to provide a mechanical torquemeasuring Wrench in which deformation of the parts of the wrench isemployed in indicating the torque applied to the wrench.

It isnalso an object of my .invention toprovide a wrench'of the abovecharacter in Awhich the parts are protected from mechanical injury.

Another object of my invention is to provide a 30 torque indicatingwrench of extremely simple construction and in which there is a minimumof friction.

' Another object of my invention is to provide a torque indicatingwrench of increased accuracy 35 over devices known to the prior art.

A more speciiic object of my invention is to proyide a torque indicatingwrench which is sum- Aciently accurate that it may readily be used as aI scale or weight measuring device. A 40 Another obiect'oi' my inventionis to provide a torque indicating wrench which is of sumclent accuracythat it may beused as a brake testing device.

Another object of my invention is to provide a device which issumciently accurate that it may be readily utilized in testing springso't all kinds.

Another object of my invention is to provide a device which may bereadily adjusted. to vary the stiffness of the ilexibleportion thereof.

Another object of vmy 'invention is to provide means for readilyadjusting the indicating device so that it shall read zero when notorque is applied.

Another object of my invention is to provide a combination torqueindicating and ratchet wrench.

Another object of my invention is to provide an improved ratchet wrenchstructure.

Other and further features and objects of the 5 invention will be moreapparent to those skilled in the artl upon a consideration of thevaccom- "pan'ying drawings and following specications. wherein isdisclosed a single exemplary embodiment of the invention, with theunderstanding, 10 however, that such changes may bemade therein Aas fallwithin the scope of the appended claims. without departing from thespirit of the invention. Y

In said drawings:

-Figure 1 is a plan view of a wrench constructed according to oneembodiment of my invention. Figure 2 is a view in horizontal section oithe wrench shown in Figure 1` Figure 3 is a view in vertical section ofthe 20 wrench shown in Figures 1 and 2.

-Figure 4 is aview invertical section of lthe head of the wrench shownin Figures 1, 2 and 3, but in enlarged relation to better illustrate theparts of the device.

. 25 Figure 5 is a view in horizontal section of a modified form of myinvention in which the torque indicating structure is combined with alratchet wrench structure. The view is in horizontal section, and

Figure 611s a view in side elevation of the embodiment of my inventionillustrated in Figure 5. A device constructed according to a preferredembodiment of my invention is comprised of a head Hl on which is mountedan indicator i l. A hollow handlel2 is received in thehead i0 and xedtherein Aby means of a set screw 9 and the outer end of the handle isprovided with a grip I3. A shaft I4 is mounted within the handle i2 andthe grip I3, and the vshaft is tapered at the inner end, as indicated ati5, to provide for a maximum movement of the inner end with reference tothe handle i2. The inner end of the shaft Il engages a gear rack I6 andthe rack is adapted to rotate a pinion l1 which is operatively 45connected to the indicating needle i8 of the indi# cator il. Obviously,other forms of operative connections may be employed for transmittingmovement of the shaft I l to the needle i8.

'The head I0 is preferably lozenge-shaped so that the large centralportion thereof serves as .a protection for the mechanism inside thehead and also for,the dial of the indicating instrument. The head isprovided with a squared shaft 55 tation thereof. The member 20 projectsfrom the ing bolts and nuts.

A cylindrical chamber or bore 22 extends through the head I0, and thecylindrical body portion 23 of the indicating instrument II is re'-ceived within one end of the bore 22. The body 23 may rotate within thebore 22. Frictional resistance to rotation of the body 23 land means forholding the body within the bore is furnished by means of a spring 24which engages a groove 25 within the body 23.' 'I'he bore 22 thusaffords an open chamber to permit ready assembly of the parts of thedevice. This chamber may be closed by means of the cap 26 which is heldin place by the set-screw 21.

Thev body 23 is provided, at the central axis thereof, with bearings 28for the shaft I9 of the indicator. The shaft I9v is adapted to receivethe needle I8 of the indicating device and has means thereon forengaging a hair spring 29 which is anchored on the body 23 by means ofapin 3|, the purpose of the hair spring 29 being to tend to rotate theshaft I9 to take up back-lash between the pinion I1 and the gear rackI6. The gear rack I 6 is engaged by the split inner end of the shaft I4and the rack is adapted to be held in the s lit end vof the shaft bymeans of the cap screw 3 The knurled rim 33 of the body 23 carries thedial 34 with it. The rim, cover, and dial may easily be rotated in thebore 22 to adjust the dial so that the needle points to zero when nostress g is applied.

The outer end of the shaft I4 is preferably held within a split sleeve4I. This split sleeve 4I may be moved in and out on the shaft I4 to thusshorten or lengthen the lever arm formed by the shaft in the handle I2,to thus vary the extent of movement of the inner end of the shaft withrespect to the head I0. Movement of the sleeve 4I with respect to theshaft I4 may be accomplshed by means of pins inserted through theopenings 45 or by removing the cap or disk 44 and withdrawing the shaftand sleeve, adjusting and replacing them.

- The split sleeve 4I is adapted to be held in place by means of a setscrew 42 which engages the grip I3 on the handle I2 and also holds thesplit sleeve 4I in gripping relation on the shaft. The shaft I4 may bemoved in and out to a limited degree by means of the threaded disc 44 tobring the gear rack I6 into proper engagement with the pinion I1. Theend of the shaft I4 is engaged to the disc 44 by means of a cap screw43. The disc 44 has openings 45 therethrough and the openings 45 servenot only as a means for rotating the disc 44, but the split sleeve 4Imay be moved forward and back through the holes 45 without disturbingmeshing of the rack I6 and pinion I1.

In operation the squared projection 20 is engaged within a suitablesocket member 2I in accordance with the usual practice and any forceapplied to the handle I2 or at the grip I3 or along the length thereofwill bend or flex the handle I2. Since the outer end of the shaft I4 isgripped in the outer end of the handle I2 the inner end of the shaft I4will move with respect to the inner end of the handle I2 and thismovement is reiiected by the gear rack I6 which will '20 pressed tightlyinto the head III to'prevent rorotate th pinion I1 to rotate the needleI8. The dial may be so calibrated that a pressure or force applied tothe handle is indicated directly in pounds or the dial may be calibratedto indicate this force in foot pounds or inch pounds or, of course, inany other desired system of force measurement.

I may `marl: the grip I3 at a selected point and calibrate the dial insuch manner that the reading of the dial will indicate directly theforce inpounds applied at the marking. In this manner I may grip thesquared portion 20 in a vise or the like and apply weight to the grip I3at the marked portion and the needle will directly indicate the weightin pounds.

I may provide a simple means for defiecting springs, to test thestiffness of the springs by means of the squared portion 20 of thetorque measuring device. The device may be utilized as a brake testingdevice. In this case, the Wheels of a motor vehicle are turned bymeanslof the squared portion 20 and a nut on the hub of the wheel, thebrake lbeing-set at selected pressures.

In a modified form of my invention illustrated in Figures 5 and 6substantially the same structure is employed except that a ratchet headIa is employed instead of the xed head I0 illustrated in Figures 1 to 4inclusive. 'I'he same inindicating structure I I is employed, togetherwith the same handle I2 and shaft I4 for actuating the indicatingdevice. In this ratchet head, however, a ratchet wheel 5I forms a pariof a shaft 52 having a squared extension 5i! and, of course, these partsmay rotate in the head Illa. The head Illa is enlarged, as indicated at53 and 54, in order that ratchet dogs 56 and 5l may be received in thehead. These ratchet dogs are resiliently held against the teeth of theratchet 5I by means of springs 58 and 59. The springs 58 and 59 are heldin place by means of threaded plugs 6I and 62. It is to be observed thatthe shoulders 63 amd64 on the dogs 56 and 5l, are so disposed that whenone of the dogs engages one tooth the other is half-Way up the slope ofanother tooth, therefore, the ratchet may have a relatively small'number of teeth which permits the use of large strong teeth and yet theWrench may be advanced l a half tooth at a time to provide for rotatingthe squared projection 50 even under conditions when the handle can bemoved to only a very limited degree.

A torque wrench provided with a ratchet feature will Work just as rwellas the fixed wrench shown, since the measuring instrument is actuated byilexing of the handle itself rather t'han depending upon a mechanismassociated with the dogs.

It is apparent that I have provided an extremely simple and desirableinstrument which is inexpensive to construct and' maintain and whichwill have a high degree of accuracy. Furthermore` I have provided meansfor ready adjustment both of the indicating device and of the handle.and of a lever Within the handle, so that the device mair be readilyadjusted for accurate reading.

Although I. have described a specific embodiment of my invention, it isapparent that modifications thereof may be made -by those skilled in theart. Such modifications may be made Without departing from the spiritand scope of the invention as set forth in the appended claims.

I claim as my invention: y

1. In a torque wrench, a head, an indicating mechanism associated withthe head, a flexible hollow handle fixed to the head, and shaft means.han

within the hanne for actuating the indicating' instrument in accordancewith the movement off flexing of the handle.

2. In a wrench, a head, an indicating means rotatably mounted inthehead, a flexible hollow handle inserted within the head, a shaft mountedwithin the handle and extending into the head, and a rack member-securedto the end of the shaft within the -head and operativelyv engaged to theindicating means.

3. In a wrench, a head, an indicating means rotaably mounted in thehead, a flexible hollow le inserted within the head, a shaft mountedwithin the handle and extending into the head, a rack member secured tothe end of the shaft within the head and operatively engaged to theindicating means, and means slidably engaged on the shaft within thehandle forregulating the effective flexible length of the handle.

l 4; The combination, in a wrench,of a hollo ilexible handle, a shaftrigidly secured at one 'end within the'handie, a head member includingmeans for engaging a nut or bolt fixed on the handle, indicating meansmounted in the head member, and means for operatively connecting theindicating means and the free end of the shaft whereby movement of theshaft is registered on the indicating means.

5. A wrench, comprising a head member, a hollow flexible handle securedin the-head member, a shaft mounted in the handle and extending into thehead member the end of the shaftopposite the head being rigidly securedto the handle, indicating means mounted in -the head member, meansoperatively connectinthe shaft member and the indicating means wherebymovement of the shaft is registered on the indicating means, and ratchetmeans mounted in the head member, the said ratchet means being adaptedto be operatively secured to a bolt or the like for the turning thereof.

6. In a wrench, a head, a hollow exible handle secured in the head, ashaft rigidly secured in the handle and extending into the head, anindicator mounted in the head, and gear and rack means operativelyconnecting the shaft and thev 7. In a wrench, a head, a exible hollowhandle secured in the head, a shaft secured in the handle and extendinginto the head. a split sleeve surrounding the shaft at one end thereofand adapted tobe slidingly positioned on the shaft, an indicator mountedin the head, and gear and rack means operatively connecting the shaftand the indicator.

8. In a wrench, a head, a hollow flexible handle secured in the head, ashaft, means for rigidly securing the shaft in the handle for adjustablepositioning therein. indicating means mounted in the head. and means foroperativeb connecting the indicating means and the shaft movement of theshaft is registered on the indicating means.- I. 9. In a wrench, a head,a socket post secured in the head, an indicating member mounted inthehead, a flexible hollow handle secured in the head, ashaft extendingwithin the handle and into the head, means for rigidly securing theshaft for adjustable positioning within the handle and the head andmeans for operatively connecting the free end of the shaft and theindicating means whereby movement of the shaft `is registered on theindicating means. .L

10. In a wrench, a head, a socket post secured in the head, anindicating member mounted in the head, a flexible hollow handle securedin the head, a'shaft extending within the handle and into the head,means for seeming the shaft for adjustable positioning wit-hin thehandle and the head, means for operatively connecting the shaft and theindicating means whereby movement of the shaft is registered on theindicating means, a-split sleeve slidably engaged on the shaft with- \inthe handle, and means for positioning the sleeve on the shaft forregulating the extent of movement of the shaft when certain forces areimparted thereto.

11. In a wrench, a. head, a hollow flexible handle secured to the head,a shaft within the handle and extending into the head, the shaft beingcoextensive with the handle and ilxed within the handle at the endopposite to the head, an indicating means on the head, and means on thefree end of the shaft within the head for driving the indicating-mechanism Ain accordance with the relative movement between the headand the free end of the shaft.

12. In a torque wrench, a. head, a pipe-like bendable handle xed to thehead, a shaft within the handle and coextensive therewith held in placewithin the bendable member at one end thereof and the other end of theshaft projecting into the head, and an indicating means mounted in thehead for indicating the degree of movement between the free end of theshaft and the bendable member.

13. In a wrench, a head, a hollow exible handie secured in the head, ashaft rigidly secured in the handle and extending into the head, an

indicator mounted in the head, and drive means msm :.DUNN.

